This invention relates to a presser foot. More specifically the present invention contemplates providing a presser foot which permits a shoe to be attached to or detached from a shank with smoothness and accuracy, and which enables the operator to easily perform a threading operation, regardless of shining on the front surface of the shank due to reflected rays.
In one type of well-known presser foot for sewing machines, a shank and a presser shoe are formed separately in two pieces.
The pressor foot comprises a shank detachably connected to the sewing machine presser foot bar, the shank being formed with a vertical groove at one side thereof for receiving the presser foot bar therein and having a transverse slot formed at the bottom to extend from side to side of the shank and a plurality of lugs extending forwardly from the back of the shank, the shank being further formed with a longitudinal bore extending forwardly from the back of the shank and opening into the transverse slot. A lever is pivotally connected to the pair of lugs, a wire is connected to the lower end of the lever and movably extends through the longitudinal bore so that its forward end projects into a transverse slot. Means including a torsion spring normally urge the wire to close at its forward end the open side of the transverse slot. A presser foot shoe has a pair of supports extending along opposite sides of the upper surface of the shoe, and a shaft mounted on the supports extends transversely of the shoe and is adapted to be received in the transverse slot formed in the shank and retained therein by the forward end portion of the wire closing the open side of the transverse slot.
In this type of presser foot described heretofore there is provided a wire connected at its base to the lower end of the lever and movably extending through the longitudinal bore by means of the lever.
The wire sometimes fails to function properly when it moves through the longitudinal bore. Its forward end may project to deeply into the transverse slot to be drawn backward, or the end may contact too tightly underneath the shaft of the shoe retained in the slot, whereby the shank becomes undetachable from the shoe. Also, the forward end of the wire may not move far enough into the slot to support the shaft, whereby the shank is not properly connected to the shoe.
The object of the present invention is to overcome the aforementioned drawbacks by providing a rod with a stopper devised to adjust distance of movement of the rod through the longitudinal bore.
The forward and backward movement of the rod through the longitudinal bore is performed by the lever urged by the biasing force of a torsion spring fitted in lugs of the presser foot. However, the torsion spring may easily be deformed by frequent uses. Accordingly, another object of this invention is to provide means to eliminate the aforementioned drawback.
Another type of well-known presser foot comprises a shank detachably connected to a sewing machine presser foot bar and a presser foot shoe undetachably connected to the shank, as compared with the first type of presser foot wherein a shank and a shoe are formed seperately in two pieces.
When threading a needle of a sewing machine equipped with either type of presser foot heretofore explained, an operator usually sits in front of the sewing machine head, facing the needle and tries to thread the needle from the front side to the rear side through the needle hole by hand.
Since the sewing machine parts, such as the needle, the needle-bar, the presser foot, are usually plated with chromium or nickel, the operator finds it difficult to locate the needle hole for threading due to reflected rays on the surface of the plated parts.
A further object of this invention is to provide a presser foot with a shank whose vertical front portion is so arranged that the reflection of light rays thereon is prevented so that the operator is able to locate the needle hole with ease, whereby threading is performed efficiently.
Other and further objects of this invention will become obvious upon an understanding of the illustrative embodiments about to be described or will be indicated in the appended claims, and various advantages not referred to herein will occur to one skilled in the art upon employment of the invention in practice.